OVERVIEW
• Reproduction is the creation of new
individuals from existing ones
• A population can exceed its finite life spans
by reproduction
• Adaptations of animal form and function will
contribute to their reproductive success
46.1: Both Asexual and Sexual
Reproduction Occur in the Animal
Kingdom
2 Modes of Animal Reproduction
• Asexual: genes of new individuals come directly
from one parent
-relies on mitotic cell division
• Sexual: new individuals created by the fusion of
gametes to form zygotes
- Increases genetic variability of offspring
- Higher chance of reproductive success
Asexual Reproduction of Sea
Anemone
Earthworms Mating Sexually
Mechanisms of Asexual
Reproduction
• Fission:
Parent separates into two or more
individuals of equal size
• Budding: New individuals arise from
outgrowths of existing ones
• Fragmentation: Body breaks down into
multiple pieces-some or all of these pieces
develop into adults
- it requires regeneration of the lost body
parts
Hydra Budding
• Video
Fission in Amoeba
Starfish using fragmentation
Yeast Cells Budding
Reproductive Cycles and
Patterns
• Reproductive cycles
are controlled by
hormonal and
environmental cues
• Parthenogenesis:
process in which egg
develops without
fertilization
Parthenogenesis in
Daphnia Eggs
Temperature
Rainfall
Lunar Cycles
Cont..
• Hermaphroditism: each
individual has male and
female reproductive
systems
- some hermaphrodites selffertilize
Lizard hermaphrodites
• Sequential
hermaphroditism:
individual reverses its sex
during its lifetime
Sex reversal in bluehead wrasse
46.2 Fertilization Depends on Mechanisms
that help sperm meet eggs of same species
• 2 types of fertilization
-External: eggs shed by female -Internal: egg and
are fertilized by sperm in external sperm unite in female
body
environment
Inside female body
External Fertilization frog
•Fertilization requires environmental cues
Ensuring the Survival of
Offspring
• Internal fertilization:
produces less zygotes
than external
- but survival rate
higher for internal
fertilization
• Parental care and
protection of embryos
results in few offspring
by internal fertilization
Male giant water bug carrying
eggs
Gamete Production and
Delivery
• Reproductive systems produce gametes and
make them available to gametes of the opposite
sex.
• Simplest Reproductive
systems do not have gonads
(gamete producing organs)
• Complex systems- accessory tubes Complex flatworm
reproductive system
and glands to protect/nourish gametes
46.3 Reproductive Organs Produce and
Transport Gametes: focus on humans
Female Reproductive Anatomy
• External: human female has vulva,
labia minora, labia majora, and
clitoris
• Internal: Vagina connected to
uterus, which connects to two
oviducts; 2 ovaries (female gonads)
have follicles containing egg cells
• Mammary glands present in male
and
female but only function in female
Female Reproductive System
Male Reproductive System
• External structures: scrotum
and penis
- testes (male gonads), are in
cool environments in
scrotum
- testes have hormone
producing cells and
seminiferous tubules leading
to tip of penis(epididymis,
vas deferens, ejac. duct,
urethra)
Male Reproductive System
Human Sexual Response
• 2 physiological reactions in both sexes:
vascongestion-filling of tissue with blood
myotonia- increased muscle tension
• 4 phases of response:
-excitement
-plateau
-orgasm
-resolution
46.4 In Humans and other mammals, a
complex interplay of hormones regulates
gametogenesis
• Oogenesis- female form of gametogenesis
(production of gametes)
• Spermatogenesis- male form
• Meiosis is essential to oogenesis and
spermatogenesis
• Differences:
- oogenesis: cytokinesis is unequal-produces
large ovum; spermatogenesis: starting cells
become 4 sperms
- oogenesis: cyclic; spermatogenesis:
constant/continual
The Reproductive Cycles of Females
•
Menstrual(Uterine) cycle:
proliferative and secretory phase
- caused by ovarian cycle
• Female reproductive cycle is one
integrated cycle
• Reproductive cycle dependent on
secretion of GnRH, FSH, and LH
Hormonal Control of Male
Reproductive System
• Androgens (steroid hormones)
from testes cause primary and
secondary sex characteristics in
males
• Androgen secretion and
production controlled by
hypothalamic and pituitary
hormones
46.5In humans and other placental mammals,
an embryo grows into a newborn in the
mother’s uterus
• Pregnancy (Gestation): carrying
one or more embryos in the
uterus
• Human pregnancy: 38 weeks
• Pregnancy time, in other species,
correlates with body size and
maturity of young at birth
Conception, Embryonic
Development and Birth
•
After meiosis and fertilization of egg,
zygote becomes blastocyst
• Human pregnancy: 3 trimeters
- Baby develops with time
- Urine contractions (parturition) causes
birth
•
3 stages of birth: dilation of cervix,
expulsion, delivery of placenta
Human Fetal Development Timeline
Three
stages of
Labor
Mother’s Immune Tolerance
of Embryo and Fetus
• Half embryo genes are from
father: foreign to mother’s body
• Trophoblast and placenta: protect
embryo from rejection in
mother’s body
- release signal molecules
- break down tryptophan
- induce “death activator” protein
(FasL)
Contraception and Abortion
• Contraception: prevention of
pregnancy
• Methods of contraception
prevent
-release of mature gametes
-fertilization
-implantation
Modern Reproductive
Technology
• Helps
- Detect any problems with
developing embryo before
birth
Ultra Sound
- People have children through
in vitro fertilization: oocytes
mixed with sperms and
incubated
Works Cited
"Female Infertility." Mayo Clinic. Mayo Foundation for
Medical Education and Research. Web. 23 Apr. 2012.
<http://www.mayoclinic.com/health/medical/IM01237>.
"Human Development." ROHAN Academic Computing.
2007. Web. 25 Apr. 2012. <http://wwwrohan.sdsu.edu/dept/phil/fetal.htm>.
"Science Clarified." Birth. 2006. Web. 24 Apr. 2012.
<http://www.scienceclarified.com/Bi-Ca/Birth.html>.